How much is too much (on the back of the judo/bjj topic)

I thought this question would be best locked up in G-Bay

I've been training BJJ and Kickboxing now for ~12 months, not long by any stretch of the imagination, really enjoying both, I'm picking things up reasonably quickly in BJJ and improving my striking and movement with kickboxing, overall I'm just really enjoy training and learning.

A few months ago, the instructor introduced a couple of Judo techniques into a 'crosstraining' class they run (think MMA style striking to clinch to ground work), suffice to say it piqued my interest in wanting to picking up some Judo techniques as well.

Currently I train 2 days kickboxing, 3 days BJJ, 3 days weights at gym.

Is there any point in doing 1 class a week of judo?

What I'm half assing around asking is, is there a point when too much, becomes detrimental and you start making slower/negative gains with crosstraining? (Obviously this would be highly subjective to individuals, some people learn faster, absorb more, can physically handle it etc etc) I'm looking more for personal experiences of people who train more than 2 or 3 (oh crap) arts, and how they cope or didn't cope with it?